Minor bug fixes

[water111]

• make sure bsp is processed on l levels in extraction (caused missing remaps)
• clean up a few prints in extraction
• handle the <15 byte differences in art group files automatically (no more errors about file naming)
• fix potential exception thrown by merc2 in a few ways: fixed bad data in FR3's, check texture index just in case, and handle exceptions a little bit better (still a crash, but at least you get a print)
• fix mips2 ocean stuff causing ocean far crashes